Consolidate price and deposit updates into a single method

[will-holley]

Summary

Currently, updating price and deposit requires separate transactions. This increases the gas cost for users who want to, for example, increase their price and increase their deposit proportionally.

Changes

@721labs/lebron-pizza has already implemented this. Examine whether this method is effective (can the positive/negative deposit system be simplified?).

[vicsn]

I would defer any gas-optimization work for the near-term - moving to ETH Layer 2 or deploying to EVM-compatible low fee chains achieves more gains

[will-holley]

One of the goals behind this project is providing a codebase that can be forked and deployed on any EVM-compatible chain. Accepting architectural limitations with the hope that low-gas obfuscates them isn't a good precedent.